You'll need to give us a bit more information before we can make suggestions.
Have you ever barrel raced before? Either way, you'll need to spend some time working on the pattern with her so that YOU can get used to how she runs (as she doesn't need the practice, if she is truly finished on the barrles), but you as the rider will need to figure her out.
Don't work on the pattern more than 2 or 3 times a week. Do not work on them every day. She will get bored working on something she already knows how to do. You can also set your barrels up in different patterns, so that you can still learn how she turns and how to manage her the best, without doing the same pattern over and over. Or teach her how to pole bend, if she doesn't already know that. Or set up random obstacles that you can maneuvar around like at a gaming show. Use your imagination!
But mostly, just spend time trail riding her. That will get you used to her and her quirks. Plus, trail riding is a great way to condition a horse as well.
If you've got cattle available to you, that is often great for a barrel racing horse's mind. And something fun you can do, while also getting some "work done" (iif you are on a ranch, anyway)
∞•*˚ Βгįťţαňγ ˚*•∞
It is not enough to know how to ride; one must know how to fall.